Abstract: Colorado is developing its own tools, such as the Colorado River Decision Support System (CRDSS), to evaluate alternative strategies and establish an informed and factual position regarding operation of the major Colorado River reservoirs and other major issues. The CRDSS will be designed to display hydrologic data in an easily accessible manner, model interactions between demands and dynamic hydrologic conditions, and determine the river system's ability to meet future demands based on operational and administrative use of storage. The CRDSS will provide the data and models to evaluate various river operating alternatives and model numerous what if' scenarios with respect to utilization of Colorado's compact apportionment, specific to Colorado's principal river basins, either separately or as a whole. Alternatives that can be addressed using the CRDSS include operational plans to realize improved efficiency of use, exchanges between water users, construction of new reservoirs (or enlargement of existing facilities), augmentation and replacement plans, and the development of additional beneficial uses such as the Colorado Water Conservation Board (CWCB) minimum streamflow program and alternatives for the protection of endangered fish species.